TSA in Cryogenic Temperatures
10-18-2007, 09:11 AM,
#1
TSA in Cryogenic Temperatures
Hi,
For a steam ejector vessel we have the following operating temperatures cases:
1. liquid cryogenic drains flow to the ejector: -196?C
2. Steam is used for blowing out the drains: +350?C
3. Ejector is normally not in operation: ambient
The plant is in sea water atmosphere.
We have proposed our Client, as standard engineering practice in our Company for this service range and atmospheric conditions to use stainless steel type 316 uncoated.
Our Client insists on coating. That we can not find a paint system to this application range our Client has proposed the use TSA.
Question: Has anybody experience with TSA in cryogenic (-196?C) services?
The ejector is an equipment with nozzles and flanges. Is there any inconvenient for application of TSA in complex surfaces?
I will appreciate very much your support on this. Actually i am looking for reasons NOT to apply TSA.
Reply
10-18-2007, 10:49 PM,
#2
RE: TSA in Cryogenic Temperatures
Hi Cachube

Sign0016 to the Surface engineering forum.

Thermal spray aluminium I think would probably be ok in these conditions (I would test it first though Happy0193). Not so sure of having it on 316 stainless steel though, as this is usually used as a anti-corrosion/heat resistant coating on carbon steels. Difficult to answer on the difficulty to spray on complex geometries without seeing part, but if any surface can not be seen by line of sight, then it it will be difficult.
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10-19-2007, 06:46 AM,
#3
RE: TSA in Cryogenic Temperatures
Thanks Gordon for your prompt reply.
As I mentioned in my query, our intention is in fact to find supporting technical reasons why TSA is not the adequate corrosion preservation application for our equipment.
The complex geometry may be one valid case. This ejector looks more like a piece of pipe with some small drain nozzles.
What is your opinion about the different material thermal expansion of aluminum and stainless steel? How will be the behaviour of aluminium coated stainless steel when in contact with -196?C cryogenic liquids receives a flow of 250?C hot steam? Here I am just interest of coarse to what can happen to the coat!!
A test is certainly not a bad idea. I wonder if some of the Forum Members would have already carried out a similar test???
Many thanks in advance for your technical advice.
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10-19-2007, 03:42 PM,
#4
RE: TSA in Cryogenic Temperatures
Hi Cachube

For the thermal shock issue, I think you will need to test to be sure. I assume you are happy with the performance 316 stainless steel in this environment, as it does seem strange that your client would consider coatings. Do they have concerns as far as chloride induced stress corrosion cracking? if so TSA may be advisable.
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10-25-2007, 01:37 PM,
#5
RE: TSA in Cryogenic Temperatures
Hi,
The best material for crygenic application at (-)196C is 9%Ni-steel in QT condition.You can get to that temperature by dipping in liquid nitrogen.Ductile to brittle transition temparture of materials are determined by conducting charpy impact tests after dipping the test specimens at various temperatures from -196C and above in a bath of liquid nitrogen plus various proportion of petroleum ether.
ram chattopadhyay
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10-26-2007, 06:36 AM, (This post was last modified: 10-26-2007, 06:39 AM by Cachube.)
#6
RE: TSA in Cryogenic Temperatures
Hi,
Thanks for your reply. Actually in looking for a solution to surface coating and not to the base material of the equipment. If we use 9%Nickel material, which is certainly suitable for cryo temp's, however we will have the same problem to find a coat which withstand cold and warm temperatures.

Thanks,
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